In scanning microscopy, a sample is scanned with a light beam in order to observe the reflection or fluorescent light emitted by the sample. Lasers are frequently used as the light source for this purpose. For example, an arrangement with a single laser that emits several laser lines is known from EP 0 495 930, “Confocal microscope system for multicolor fluorescence.” Currently, mixed gas lasers, in particular ArKr lasers are usually used for the purpose. The focus of an illumination light beam is moved in an object plane with the help of a maneuverable beam deflector, generally by tipping two mirrors, whereby the axes of deflection are usually positioned perpendicular to each other, so that one mirror deflects in the x-direction and the other in the y-direction. The mirrors are tipped with the help, for example, of galvanometric positioners. The power of the light coming from the object is measured dependent on the position of the scanning beam. Generally, the positioners are provided with sensors to determine the actual position of the mirrors.
In confocal scanning microscopy in particular, an object is scanned in three dimensions with the focus of a light beam.
A confocal scanning microscope generally comprises a light source, a focusing optic with which the light from the source is focused on a pinhole aperture—the so-called excitation aperture—, a beam splitter, a beam deflector to control the beam, a microscope optic, a detection aperture, and detectors to detect the detection light or fluorescent light, as the case may be. The illumination light is coupled via the beam splitter. The fluorescent light or reflection light coming from the object returns to the beam splitter via the beam deflector, passes through it, and finally focuses on the detection aperture, behind which are the detectors. Detection light that does not originate directly from the focal region takes another light path and does not pass through the detection aperture, so that pixel information is obtained that leads to a three-dimensional image as a result of sequential scanning of the object. In most cases, a three-dimensional image is achieved by layered data imaging, whereby the path of the scanning light beam ideally describes a meander on or in the object. (Scanning a line in the x-direction at a constant y-position, then interrupting x-scanning and y-repositioning to the next line to be scanned, and then scanning this line at a constant y-position in negative x-direction, etc.). To enable layered data imaging, the sample table or the objective is repositioned after scanning a layer so that the next layer to be scanned is brought into the focal plane of the objective.
A multicolor spotlight source for a laser scanning microscope is known from DE 196 33 185. The multicolor spotlight source has at least two lasers of different wavelengths, which scan over the sample, that produce a multicolor spot on a sample to be tested, whereby a beam combiner is provided that is optically connected with the lasers, is located between the laser scanning microscope and the lasers, and coaxially combines the laser beams of the laser. A possible developmental variant provides that a laser is coupled directly and other lasers are coupled via light-guiding fibers in the beam combiner. The beam combiner is designed as a monolithic unit. A light guide, which transmits all of the coaxially combined beams from all lasers to the laser scanning microscope is provided between the beam combiner and the laser scanning microscope, whereby the laser beams are adjustable on this light guide.
An optical fiber switching device with a displaceable light-guiding fiber and a production method are known from DE 102 51 897 A1. The optical fiber switching device comprises at least one displaceable light-guiding fiber and at least one control electrode to produce an electrostatic field, which controls the spatial position of the displaceable light-guiding fiber to the optical coupling with at least one second light-guiding fiber. In order to disclose an improved optical fiber switching device, the switching device has an electrically isolating housing, the inner wall of which is partly formed by at least one control electrode.
Generally in microscopy, if a microscope is provided with several light sources, a dichroic or dichromatic beam splitter is used to combine the beam paths of the light sources. Additional components such as acousto-optical filters (AOTF), which are complicated to adjust, are necessary to control the light power of the individual lights emitted by the light sources. Combining beams with conventional optics is therefore both space consuming and very costly. Further disadvantages include the great complexity of adjustment and the susceptibility to interference.